Multitasking and performance measurement

In a principal-agent setting, we consider a combined problem of multitasking and performance measurement. The principal can choose to reward the agent both directly for providing effort into a specific activity, and based on the outcome delivered to the principal. Both the issue of multitasking and any private knowledge the agent might possess will lead the principal to use a performance measurement more. This applies even if the measurement is poorly correlated with the actual outcome to the principal.